Corten I Assume
A simple metal firepit, which I assume is made from the same Corten steel as the planter.
New Corten steel starts off looking like ordinary steel , then develops a layer of rust, giving it that industrial rustic look that some people like the look of.
Before you decide on using Corten in your garden, please search online for “corten staining”. During the rusting process, rain will wash the powdery orange rust from the steel, and can cause ugly orange stain on your nice new patio.
We make our firepit tables from Stainless steel. It’s called ‘Stain Less’ for a very good reason. I think they should rename corten as ‘stainmore’. That’s just my opinion.